Sustained-release delivery devices are usually a very satisfactory administration method for certain drugs, in particular (but not limited to) drugs for patients in need of a treatment for diseases such as schizophrenia. Some treatments for disorders usually involve daily oral tablets or solutions. However, one of the intrinsic problems of these treatments is the dissociation (non-compliance) of some schizophrenic patients from the treatment, especially when therapy requires daily administration. Non-compliance leads to irregular or inconstant treatments and favors the appearance of psychotic crisis or episodes. Moreover, oral tablet therapy gives rise to high fluctuations in the plasma levels (measured as the difference between Cmax and Cmin) in patients, therefore usually affecting the patient's mood. On the contrary, administration of sustained-release delivery devices should provide adequate drug delivery to a patient for extended periods of time with just one dose and without the need of caregivers to pay attention to a daily medication, thereby providing more homogeneous plasma levels in the patient.
One of the most common ways to administer certain drugs presently is through the use of depot injections. Depot injections allow careful control of drug usage (as opposed to orally administered drugs) and ensure regular contact between the caregivers' team and the patient, where overall treatment efficacy and/or side effects may be identified. Furthermore, it is easy to identify defaulters (non-compliant patients) and prepare interventions. However, in situ forming implants currently described in the state of the art cannot properly control drug release from the implant, and fail to provide therapeutic plasma levels sufficient for a bi-weekly administration protocol while exhibiting reasonable differences between maximum and minimum plasma concentrations.
For example, the long-acting injectable risperidone formulation, Risperdal Consta®, is the first depot atypical antipsychotic drug in the market. It is an intramuscular risperidone-containing PLGA microparticle formulation, and it is intended to deliver therapeutic levels of risperidone suitable for bi-weekly administration. However, due to the inherent lag phase of most microparticle-based products, the patient is required to supplement the first weeks with daily doses of oral risperidone after first administration. Approximately three weeks after a single intramuscular injection of Risperdal Consta® and concurrent daily doses of oral risperidone, the microspheres release sufficient risperidone in the systemic circulation that the patient can discontinue supplementation with daily doses of the oral therapy. However, this period of oral supplementation could be a risk factor of non-compliance. Also, the presence in the body of two doses at the same time could present a potential risk of adverse events, such as irregular formulation behaviour and toxicity.
The compositions and devices of the invention, on the contrary, can evoke therapeutic drug plasma levels from the first day and for at least 14 days, avoiding the need of supplementary oral daily therapy from the administration moment. These compositions can also reduce the differences between Cmax and Cmin as observed with daily-administered oral tablets and subsequently may reduce variations in the patient mood. In addition, they can also cover a period within administrations that is at least as long as the period covered by currently marketed extended-release risperidone formulations.
A biodegradable copolymer poly(DL-lactide-co-glycolide) matrix has been used in medical products, such as sutures described in U.S. Pat. No. 3,636,956 by Schneider, surgical clips and staples described in U.S. Pat. No. 4,523,591 by Kaplan et al., and drug delivery systems described in U.S. Pat. No. 3,773,919 by Boswell et al. However, most of the existing formulations using these biodegradable polymers require manufacturing of an implantable device in solid form prior to the administration into the body, which device is then inserted through an incision or is suspended in a vehicle and then injected. In such instances, the drug is incorporated into the polymer and the mixture is shaped into a certain form such as a cylinder, disc, or fibre for implantation. With such solid implants, the drug delivery system has to be inserted into the body through an incision. These incisions are sometimes larger than desired by the medical profession and occasionally lead to a reluctance of the patients to accept such an implant or drug delivery system.
U.S. Pat. No. 8,221,778 to Siegel et al. (corresponding to WO 2005/070332) discloses an implant containing risperidone (10-60% wt) and PLGA (90-40% wt) having a lactic acid to glycolic acid ratio of 50:50 to 100:0. These implants are not formed in situ.
Injectable biodegradable polymeric matrix implants based on lactic acid, glycolic acid and/or their copolymers for sustained release have already been described in the art. U.S. Pat. No. 5,620,700 issued to Berggren describes a bioerodible oligomer or polymer material containing drug for local application into a diseased tissue pocket such as a periodontal pocket. However, the material requires heating to high temperatures to become sufficiently flowable to allow the injection, so that hardening of the material after cooling to the body temperature conforms the implant.
U.S. Pat. No. 6,143,314 to Chandrashekar discloses an injectable composition that forms an implant in situ. The composition is made of drug, organic solvent and a PLGA/PEG block copolymer.
U.S. Pat. No. 6,673,767 issued to Brodbeck describes procedures to for in situ formation of biodegradable implants by using biocompatible polymers and biocompatible low water-miscible solvents. A viscous polymeric solution containing the drug, that upon injection releases the drug in a controlled manner, can be obtained through the use of low water-soluble solvents. Solvents with low water-solubility (less than 7% miscibility in water) are used as a method to reduce the release of the drug in aqueous mediums, allowing initial drug releases of 10% or lower during the first 24 hours. However, in our experience, the use of water-immiscible and/or low water-miscible solvents cannot satisfactorily control the initial in vivo release of risperidone during the first 24 hours. For example, the use of benzyl alcohol, a solvent specifically disclosed in U.S. Pat. No. 6,673,767, causes very high plasma levels of risperidone in the first 3 days and then the plasma levels decrease to very low levels in 7 days.
U.S. Pat. No. 6,331,311 issued to Brodbeck also discloses injectable depot compositions comprising a biocompatible polymer such as PLGA, a solvent such as N-methyl-2-pyrrolidone and a beneficial agent such as a drug, further comprising an emulsifying agent such as polyols. However, the compositions disclosed do not perform satisfactorily when the beneficial agent is risperidone because the use of a two-phase composition with emulsifying agents accelerates implant hydration and increases effective releasing surface area, impairing the control on the initial burst release and originating a fast decrease in drug release from the first days to the following ones. For example, a comparator composition was prepared according to the '311 patent. A container containing risperidone (150 mg), PLGA (300 mg, having an inherent viscosity of 0.32 dl/g and irradiated by β-irradiation to a dose of 25 KGy) and NMP (700 mg) was prepared. Another container containing polyvinyl alcohol in water (1 ml of a 2% wt/v). The contents of the containers were mixed, then the mixture was transferred to a syringe and injected intramuscularly (an amount equivalent to 2.5 mg risperidone) into the gluteus of New Zealand White rabbits (n=3). More than 70% of the total AUC of active moiety was released within the first 5 days after the injection. Such a formulation is unable to provide therapeutic plasma levels of risperidone for a period of at least two weeks.
U.S. Pat. No. 4,938,763, issued to Dunn et al., discloses a method for an injectable in situ forming implant. A biodegradable polymer or copolymer dissolved in a water-miscible solvent with a biologically active agent either is dissolved or dispersed within the polymeric solution. Once the polymeric solution is exposed to body fluids, the solvent diffuses and the polymer solidifies thereby entrapping the drug within the polymer matrix. Even though Dunn et al. discloses the use of water miscible solvents for obtaining in situ forming polymeric implants, it discloses a number of polymers and solvents and even proportions between the different ingredients that do not produce a satisfactory implant with the appropriate release characteristics, particularly when the implant contains risperidone as active principle. For example, a comparator composition was prepared according to the '763 patent. A container containing risperidone (50 mg) and PLGA (784 mg, monomer ratio of lactic acid to glycolic acid monomer of 75:25, and having an inherent viscosity of 0.20 dl/g was prepared. Another container containing NMP (1666 mg) was prepared. The contents of the containers were mixed. Then the mixture was transferred to a syringe and a portion (1250 mg, corresponding to 25 mg of risperidone) was injected into an aqueous liquid to determine its in vitro release profile. More than 50% of the risperidone was released within the first 2 days. Such a formulation is unable to provide therapeutic plasma levels of risperidone for a period of at least two weeks.
Another way to avoid surgery to administer these drugs is the injection of small-sized polymeric particles, microspheres or microparticles containing the respective drug. U.S. Pat. No. 4,389,330 and U.S. Pat. No. 4,530,840 describe a method for the preparation of biodegradable microparticles. U.S. Pat. No. 5,688,801 and U.S. Pat. No. 6,803,055 disclose microencapsulation of 1,2-benzazoles into polymeric particles to achieve a drug release over extended periods of time in the treatment of mental disorders. These microparticles require re-suspension into aqueous solvents prior to the injection. These formulations do not form a single (nonparticulate) solid implant.
U.S. Pat. No. 5,770,231 describes a method for producing biodegradable microparticles for sustained release of risperidone and 9-hydroxy-risperidone by dissolving the drug within an organic phase. However, the use of organic solvents that are able to dissolve the risperidone mostly or completely gives rise to very high initial plasma levels of risperidone due to the diffusion of the drug along with the diffusion of the solvent.
U.S. Pat. No. 7,118,763 describes two methods of making multi-phase sustained-release microparticle formulations based on the combination of different particle sizes or microparticles exhibiting different release profiles. The combination of two different release profiles allows the release of the drug for periods longer than two weeks. However, in practice this combination requires a mixture of particles from at least two different batches, involving the multiplication of end product specifications and increasing batch-to-batch variability. In addition, although microparticle formulations can be administered by injection, they cannot always satisfy the demand for a biodegradable implant because they sometimes present difficulties in the large-scale production. Moreover, in case of any medical complication after injection, they are much more difficult to remove from the body than implantable compositions such as those of the invention, which form a single body.
The art also discloses sustained-release delivery devices comprising a drug, PLGA as polymer and a water-miscible solvent such as n-methyl-pyrrolidone (NMP) or dimethyl sulfoxide (DMSO). However, in practice the experiments disclosed nearly in every case use NMP as solvent (WO 2004081196, WO 2001035929, WO 2008153611) or need different additives to control the initial burst (WO 2000024374, WO 2002038185, WO2008100576).
The compositions already described in the state of the art do not provide implants adequate for extended periods of treatment, such as chronic treatment compositions, kits and devices. In summary, there still exists a need of compositions and devices for sustained-released delivery systems providing a controlled, constant release of the drug from the very first day, avoiding irregular initial bursts, and showing controlled release profile during prolonged periods of time.